Joule Ringer!

[Pirate88179]

May be it is off topic, I did some tests about the power consumption when driving a CFL by help of a fly back transformer:

Attached see a circuit which is in essence a MOSFET with a pulse width modulated signal at its gate. The MOSFET drives the primary of a fly back transformer.

By programming a TI-launch pad

http://processors.wiki.ti.com/index.php/MSP430_LaunchPad_(MSP-EXP430G2)?DCMP=launchpad&HQS=Other+OT+launchpadwiki

I can create whatever pulse signal I want.

The best result is a 300 Hz signal with a 0.9% duty cycle. At 2 Volts it lights up a 15 Watt CFL with about 3 mA.  This 6 Milliwatt operation is the lowest I could get. The CFL is nicely visible in the dark (like a night light) but does not have any use.

To get useful light I need 10.000 Hz with a duty cycle of 30%. This means 150 mA at 2 Volt, i.e. 0.3 Watt.

If one is modest, 3000 Hz with a duty cycle of 8% needs about 25 mA at 2 Volt, i.e. 50 Milliwatt, and produces a modest light which allows you to pass through a room without hitting anything.

Never mind the crude contraption, it is only to test many MOSFETs and fly back transformers. I will build a nicer lamp, but the program still needs some more work. The microprocessor needs less than a Milliwatt an the whole Launch Pad costs less than 5 Euros (including the USB-cable), so it can stay in the finished lamp.

The MOSFET used is crutial, because many MOSFETS do not operate well below 3 Volt.

The best I found: VISHAY SILICONIX - SI2377EDS-T1-GE3 - MOSFET,P KANAL,20V,4.4A,DIODE,ESD,SOT23
Farnell Order Code: 1858946  (0.48 Euro)
0.1 Ohm at 1.8 Volt
(this MOSFET is terribly small, a pain to solder and to use, P-channel, 1 = OFF, 0 = ON)

This experiment serves to show what sort of low power operation of a CFL can be done with "conventional means".

But LaserSaber's circuit and his famous transformer seem to light a CFL much more efficiently, although it seems to need quite a high Voltage (up to 80 Volt) to start it up and to work for some minutes on an electrolytic capacitor. (The initial power input might well be in the Watts.)

This experiment also shows that it is indeed necessary to build "something unconventional" to have it "ring" for some minutes with only an electrolytic capacitor.

Greetings, Conrad

Conrad:

Very nice build over there.  I have used a JT outputting about 1,000 volts to light a cfl and I still did not like the light output.  This was from an AA battery and I have no idea what the amp draw was.  I am working now with led bulbs designed to run on grid power and they are waaaay brighter than any cfl I ever did on about 350-400 volts. (Also powered by a single AA.)

Bill

[conradelektro]

Bill:

The way to go is of course LEDs, if saving power when producing light is the objective.

But a big spiral CFL when softly glowing in the dark (with little power) is very cool and I like to use it instead of a candle, just for the effect.

By using different pulses, the light from the CFL can be from orange to white. Not useful, but nice.

I will test LEDs with my microprocessor/MOSFET combination, using an air coil. This should give a nice reading light with 100 Milliwatts. A Joule Thief would be better in the sense, that the batteries can run lower and it still works. The microprocessor stops working at 1.8 Volt, but one can keep the brightness constant over the falling Voltage (from 3 volt to 1.8 Volt when using 2 batteries). Using three batteries (4.5 down to 1.8 Volts) would allow to run them down to 0.6 Volts each.

Greetings, Conrad

[Pirate88179]

Conrad:

I understand.  If you are interested, check out my latest video where i compare my newest JT powered twin led bulb light to that of a JT driven cfl:

http://www.youtube.com/watch?v=qb7HUuFFJnM

The shutter on my cam ramps down and it is a little hard to see the real difference but, my single led bulb (27 chip leds) is at least 2 times as much light as the cfl circuit.  Then I show my twin set-up which is way brighter still.  I will do amp draw tests as I have been asked for them but, I have been running these lights for a while now and they are still bright so , I am guessing it is not all that high.

Bill

[conradelektro]

Conrad:

I understand.  If you are interested, check out my latest video where i compare my newest JT powered twin led bulb light to that of a JT driven cfl:

http://www.youtube.com/watch?v=qb7HUuFFJnM

Bill

A question concerning these LED bulb lights:

They are intended for 110V alternating current (in the USA)? Do you remove anything from the base of the lamp to use them with the FUJI-circuit?

Greetings, Conrad

[Pirate88179]

Conrad:

No.  I just hook them up the way they come from the store.

Bill